Cell-Environment Interaction (outside-in) Min Huang BIOE

Cells Interact with Their Environment

ECM

MECHANICAL CONTROL OF CELL FUNCTION AND TISSUE DEVELOPMENT Cellular mechano transduction Geometric Control of Cell Growth Development

Integrin: mechanoreceptors Focal adhesion functions as a nanoscale mechanochemical machine that mediates cellular mechanotransduction.

Forces applied to integrins at one point on the cell surface can be rapidly channeled across interconnected cytoskeletal elements to multiple locations distributed throughout the entire cell and nucleus. Long-distance force transfer across the prestressed cytoskeletal framework enables transcellular mechanical signaling to occur much more rapidly than chemical signaling.

Cells communicate through ECM to affect Cell shape

Q: cell shape distortion influences cell growth and function? Cell spreading and growth increase in parallel when anchorage-dependent cells are cultured on increasing molecular coating densities of ECM molecules, such as fibronectin, laminin, or different collagen types. Weakening: increasing ECM molecular densities also promotes integrin clustering, which can induce chemical signaling independently of cell shape distortion.

Soft-lithography Individual cells are cultured on single cell sized adhesive islands coated with a high ECM coating density (i.e., which promotes optimal integrin clustering) surrounded by non-adhesive barrier regions. The only experimental variable would be the degree to which cells physically distort and change shape.

Endothelial cells growth vs. apoptosis

Differentiation (forming tubes) vs. growth

Endothelial cells on square fibronectin islands preferentially extend new cell processes from their corners.

Focal adhesion formation in these regions and further increases cell prestress through activation of the small GTPase Rho; Rac acitvated 1min later.

Human MSCs are cultured on microfabricated ECM- coated islands in the presence of a mixture of soluble inducing factors, virtually all of the spread cells on large islands differentiate into bone cells, whereas all of the round cells on small islands turn into fat cells.

Human MSCs are cultured on ECM-coated polyacrylamide substrates with different mechanical compliances that match those of living tissues, cells on rigid ECMs that mimic bone osteoid differentiate into bone cells, cells on less rigid substrates that mimic muscle form skeletal muscle cells, and MSCs on ECMs with the highly flexible properties of brain tissue become nerve cells.

Cell-generated tensional forces, ECM mechanics, and cell shape distortion appear to play a fundamental role in developmental control.

Mouse embryonic lung development Activate Rho Disrupt or suppress cytoskeletal tension generation

Matrix elasticity controls vessel formation via TFII-I and GATA2 in vivo

References From cellular mechanotransduction to biologically inspired engineering: 2009 Pritzker Award Lecture, BMES Annual Meeting October 10, Ingber DE. Ann Biomed Eng Mar;38(3): Geometric control of cell life and death. Chen CS, Mrksich M, Huang S, Whitesides GM, Ingber DE. Science May 30;276(5317): Geometric control of switching between growth, apoptosis, and differentiation during angiogenesis using micropatterned substrates. Dike LE, Chen CS, Mrksich M, Tien J, Whitesides GM, Ingber DE. In Vitro Cell Dev Biol Anim Sep;35(8): Directional control of lamellipodia extension by constraining cell shape and orienting cell tractional forces. Parker KK, Brock AL, Brangwynne C, Mannix RJ, Wang N, Ostuni E, Geisse NA, Adams JC, Whitesides GM, Ingber DE. FASEB J Aug;16(10): Cell shape, cytoskeletal tension, and RhoA regulate stem cell lineage commitment. McBeath, R., D. M. Pirone, C. M. Nelson, K. Bhadriraju, and C. S. Chen. Dev. Cell 6:483–495,2004. Matrix elasticity directs stem cell lineage specification. Engler, A. J., S. Sen, H. L. Sweeney, and D. E. Discher. Cell 126:677–689, Role of RhoA, mDia, and ROCK in cell shape-dependent control of the Skp2-p27kip1 pathway and the G1/S transition. Mammoto A, Huang S, Moore K, Oh P, Ingber DE. J Biol Chem Jun 18;279(25): Control of basement membrane remodeling and epithelial branching morphogenesis in embryonic lung by Rho and cytoskeletal tension. Moore KA, Polte T, Huang S, Shi B, Alsberg E, Sunday ME, Ingber DE. Dev Dyn Feb;232(2): A mechanosensitive transcriptional mechanism that controls angiogenesis. Mammoto, A., K. Connor, T. Mammoto, C. Aderman, G. Mostoslavsky, L. E. H. Smith, and D. E. Ingber. Nature 457:1103–1108, 2009.